Organic containing sludge to fertilizer alkaline conversion process

ABSTRACT

This invention is directed to systems, devices and methods for treating organic-containing sludges and converting such sludges to high value fertilizers containing both inorganic and organic fertilizer components, which creates an inorganically-augmented bioorganic fertilizer. The invention describes methods to create a thixotrophic or paste-like material via the application of mixing energy to the organic sludge followed by an alkaline treatment and a subsequent ammoniation. The invention further describes a method to increase the plant nutrient content in the organic containing product to a level which permits the finished granular fertilizer product to compete in the commercial agricultural fertilizer marketplace. Further, the invention reduces odors associated with said organic-containing sludges.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/705,813 entitled “Organic Fertilizer Made by Alkaline ConversionProcess” filed Feb. 15, 2010, and issued as U.S. Pat. No. 7,947,105 onMay 24, 2011, which is a continuation of U.S. patent application Ser.No. 11/521,604 entitled “Organic Containing Sludge to FertilizerAlkaline Conversion Process” filed Sep. 15, 2006, and issued as U.S.Pat. No. 7,662,206 on Feb. 16, 2010, and claims priority to U.S.Provisional Application No. 60/716,964, entitled “Organic SludgeFertilizer Conversion Process,” filed Sep. 15, 2005, the entirety ofwhich is specifically incorporated by reference.

BACKGROUND

1. Field of the Invention

This invention is directed to fertilizers and methods for treatingbiosolids such as organic-containing sludges and alkaline materialsthereby converting them into useful inorganic-organic nutrientfertilizers. The invention is also directed to treatment of sludges orbiosolids to reduce noxious odorants prior to drying steps inmanufacture of organic containing fertilizers.

2. Description of the Background

There are a number of methods currently available for converting organicmaterials into fertilizers. Examples of such organic materials include,animal residuals and manures, sewage sludge, lagoon sludges,pharmaceutical fermentation sludges, food fermentation sludges and othermicrobial digested organic materials such as blood meal, fishby-products and meal, food wastes, food processing wastes and animalremains such as slaughterhouse wastes (all hereinafter referred to as“biosolids”).

When these organic-containing materials are manufactured intofertilizers, very often they contain low levels of the important plantnutrients, nitrogen, phosphorus and potassium. This limits theirusefulness and marketability in commercial agriculture which appliesvalue to a fertilizer based upon its nutrient content, especially thenitrogen and phosphorus concentrations in dry weight. This is especiallytrue of products manufactured from municipal biosolids as the nitrogenlevel in biosolids on a dry weight basis is usually 3 to 5 percent. Theimplications of a low fertilizer nutrient level are low market valuewith concomitant limitations on the distance these materials can betransported from their manufacturing site. In contrast, high nitrogenfertilizers (products containing over 8 percent nitrogen by dry weightand especially products over 12 percent nitrogen by dry weight) can betransported thousands of miles to wholesale and retail markets.

A few organic products can be purchased “fortified” for a highernutrient analysis. The ingredients used to fortify organic fertilizersare generally inorganic fertilizer components which because thesealready are fertilizers are expense, for example, ammonium nitrate,ammonium sulfate, ammonium phosphate or urea and various sources ofpotash (potassium) such as potassium oxides and greensand.

Organic fertilizers depend on soil organisms to break them down torelease nutrients; therefore, most are effective only when soil is moistand warm enough for the microorganisms to be active. Nutrient release bymicrobial activity, in general, occurs over a fairly long time period.One potential drawback is that the organic fertilizer may not releaseenough of their principal nutrient when the plant needs it for growth.

Biosolids or dewatered sewer sludge is a recycled product of municipalsewage treatment plants. Two forms are commonly available: activated andcomposted. Activated sludge has higher concentrations of nutrients(approximately 5-3-0) than composted sludge. It is usually sold in adry, granular form for use as a general purpose, long lasting,non-burning fertilizer. Composted sludge is used-primarily as a soilamendment or horticulture material and has a lower nutrient content(approximately 1-2-0) because the microbial activity in the compostingprocess has caused the logs of nutrients into the atmosphere.

Compared to synthetic fertilizer formulations, organic fertilizerscontain relatively low concentrations of actual nutrients, but theyperform important functions which the synthetic formulations do not.They increase the organic content and consequently the water-holdingcapacity of the soil. They improve the physical structure of the soilwhich allows more air to get to plant roots. Where organic sources areused for fertilizer, bacterial and fungal activity increases in thesoil. Mycorrhizal fungi which make other nutrients more available toplants thrive in soil where the organic matter content is high.Organically derived plant nutrients are slow to leach from the soilmaking them less likely to contribute to water pollution than syntheticfertilizers.

There is concern with long term effects of using biosolids products inagriculture, particularly around edible crops, in the prior art.Possible negative effects varied with the origin of the biosolids andwith the characteristics of the biosolids, for example, the level ofdisinfection that was applied to the biosolids prior to its usage and tothe level of metals that were contained in the biosolids. Manycommercial biosolids processing technologies produce what is classed bythe United States Environmental Protection Agency as a Class Bbiosolids. This type of biosolids still has potential pathogens presentbecause of the milder stringency permitted in the processing of thesebiosolids as compared to the high stringency Class A biosolids. Themajority of biosolids processed in the United States in 2006 are stillprocessed using Class B type protocols. A third concern regardingbiosolids safety is their potential containment of personalpharmaceuticals or bio-active compounds such as antibiotics. Very fewcommercial biosolids processing methodologies have the mechanisms toeliminate these types of materials. Thus there is a need for saferorganic fertilizers made from organic sludge.

SUMMARY

The present invention overcomes the problems and disadvantagesassociated with current strategies and designs for the production offertilizers containing organic components. The invention provides newtools and methods for converting organic containing materials into safeand valuable nutrient fertilizers that are marketable in commercialagriculture.

This invention is directed to systems, devices and methods for treatingorganic-containing sludges such as, for example, municipal biosolids,manures, animal residuals, pharmaceutical wastes, lagoon sludges,fermentation wastes and combinations thereof. These methods destroys thepathogens contained in such sludges, especially municipal biosolids andmanures and in the final product creates a Class A product as defined bythe U.S. EPA. The present invention also increases the plant nutrientcontent; especially nitrogen, phosphorus and/or potassium and iron insuch organic-containing sludges. The present invention describes amethod which incorporates a significant alkaline treatment and ammoniaexposure to create a strong antimicrobial stress on the microorganismspresent immediately prior to an acidification of the material whichcaptures or fixes the ammonia present into ammonium salts which arecomponents of plant nutrient fertilizers. The present invention convertsdewatered municipal wastewater biosolids or other organic-containingsludges to a fertilizer comprising sufficient organic and inorganicplant nutrients to be valuable and saleable into the commercialagricultural industry and also, secondarily, reduces the odorsassociated with such organic sludges.

The present invention is also directed to processes for convertingmunicipal biosolids, manures or animal residuals, or other biologicaland organic-containing sludges into fertilizers. The invention initiallycreates a thixotrophic or plastic homogenous paste of the biosolids withno water addition. This is followed by a significant alkaline, pHincrease or pulse to above pH 10.0 coupled with an ammonification of themix to: a) create a strong antimicrobial stress; b) further improveodors, and; c) simultaneously introduce nitrogen into the mix. Thisammonification is followed by an acidification using concentratedphosphoric acid and/or, sulfuric acid to a) fix the ammonia intoammonium phosphate and or ammonium sulfate; b) create an acid stress, onthe alkaline and ammonia exposed microbes, and; c) to introducephosphate and sulfur into the mix to create nutrient value in thefinished product. If the organic-containing sludge is noxiously odorousthen an oxidation step can be inserted in which a strong oxidant,preferably, potassium or calcium ferrate, is reacted with the mix tointeract with a significant portion of the reduced sulfur compounds,amines and other organic molecules including odorants such that they arepartially oxidized and rendered less odorous.

In addition, the present invention is directed to process hereindescribed further including the addition of chemicals to the fertilizermix such as one or more oxidants such as, for example, hypochloritessuch as section) hypochlorite or calcium hypochlorite, iron oxides,other metal oxides, calcium ferrate, potassium ferrate, or sodiumferrate, oxygen, hydrogen peroxide, other peroxides, ozone and chlorine,dioxide to further reduce odors. As further elaborated in U.S. patentapplication Ser. Nos. 11/359,751 and 11/371,238 (both of which arehereby incorporated by reference) other nutrients can be added withgranulation agents to facilitate the creation of extrusions or granulesthat are hard, dry, between pH 5.6 and pH 7.5 and valuable on thecommodity agricultural fertilizer market. This process would competeextremely well against alkaline stabilized biosolids containingprocesses and their resultant products in that less calcium oxide orcalcium hydroxide would need to be used, if at all, and the significantalkaline and disinfecting agent, ammonia, contributes significantnitrogen value to the finished product. The process and resultingproducts would be considered USEPA Class A biosolids containing productsand would commercially compete well against the heat-dried biosolidspellets as manufactured at many municipal wastewater treatment plants(“WWTPs”) presently throughout the U.S. and the world as well as ofcourse the traditional alkaline-stabilized biosolids products.

Other embodiments and advantages of the invention are set forth in partin the description, which follows, and in part, may be obvious from thisdescription, or may be learned from the practice of the invention.

DESCRIPTION OF THE FIGURES

FIG. 1 Diagram of pH during process steps of “Alkaline Ammonia Pulse”Process.

FIG. 2 Schematic Diagram of “Alkaline Ammonia Pulse” Process.

DESCRIPTION OF THE INVENTION

As embodied and broadly described herein, the present invention isdirected to systems, devices and methods for treating organic containingsludges and producing an inorganically-enhanced bioorganic fertilizer.

The “inorganically-enhanced bioorganic fertilizer” is produced in amethod of processing organic containing sludges to a microbially safecondition simultaneously with combining such sludges with plantnutrients containing nitrogen, phosphate, potassium along with sulfurand iron.

It has been surprisingly discovered that by chemically modifying organiccontaining sludges to fit the needs of nitrogen, phosphorus and/orpotassium fertilizer requirements by reacting them with hot, molten oroxidative compounds of nitrogen, phosphate and other plant nutrientslike potassium, sulfur, iron, and/or calcium creates a unique andvaluable product. The results are a product with at least: a) enhancedcommercial valuation, b) reduced odor; and, c) increased nitrogen,phosphorus, iron or other plant nutrients, e.g., potassium and/orsulfur. Significantly, the treated finished product, because it containsa high level of nutrient and is made to contain the physicalcharacteristics of commercial fertilizers, can be sold as is into thecommercial marketplace, in other words, without further modification orsupplementation as is required with other materials. The advantagesassociated with the present invention over the state of the art includeone or more of the following: combination of high concentration ofinorganic plant nutrients with an unusually high concentration oforganics in the same fertilizer granule, binding of the organics withthe inorganic ammonium ions, production of a safer biosolids or organicsludge containing product, reduction of odors of the dried fertilizerproduct, increased nitrogen content in the product, increased phosphoruscontent in the product, increased iron content in the product, increasedsulfur content in the product and/or increased potassium content in theproduct and/or increasing the calcium content or other mineral contentin the product.

The conventional method for treating municipal wastewater sludge is tomake products that are safe from a public health standpoint, preferablyachieving the U.S. EPA's Class A standard for biosolids containingproducts. The problem is that these products generally have such lowcommercial value that they have difficulty moving consistently into thecommercial marketplace especially at distances over 200 miles from thesite of manufacture. As a consequence of this, these biosolids productsare either sold for a few dollars per ton or given away or even commonlyburied to simply dispose of them. The present invention integrates plantnutrients into the finished product which increases the value of thefinished fertilizer and may, as a secondary effect, reduce said odorsassociated with the finished product.

By using aqueous ammonia instead of anhydrous ammonia as a disinfectantand simultaneously as a source of nitrogen, the manufacturing processavoids the restrictions and prohibitions that exist in many communitiesfrom transporting or working with the potentially hazardous anhydrousammonia material.

Preferably, the process of the invention may be established close to orat existing or new wastewater treatment plants if processing municipalbiosolids. If processing a manure or animal waste or biological sludgeas in from a fermentation process, it is preferable that the processingplant be constructed as near to the source as possible. Logistics andliability can be minimized by the close association of the inorganicallyaugmented bioorganic fertilizer plant with the biosolids or organiccontaining sludge source.

The present invention teaches improving the odorant quality of thebiosolids that are fed to a granulation and heat drying step andimproving the odorant quality of the finished fertilizer by introducingchemical additives to react with odorants within the biosolids, and byplacing a coating on the granules or pellets produced thereby reducingthe rate at which remaining odorants emit from the finished pelletproduct. Such a coating also reduces the dusting of said pellets duringstorage, transport and application thereby further improving their valueand usefulness.

The present invention introduces significant chemical stresses tomicroorganisms that are contained in the dewatered biosolids during themanufacturing process. For example, the treatment of the slightlyalkaline biosolids, normally found between pH 7.0 and pH 9.0 to atreatment pH of greater than pH 10 and preferably greater than pH 11causes the ammonium ions present in the mix to convert to gaseousammonia. This free ammonia begins the disinfection process for the mix.Further, the present invention teaches that either aqueous ammonia, oranhydrous ammonia, can be directly added to the mix to further increasethe concentration of free ammonia and continue the disinfection process.The concentration of free ammonia should meet or exceed 2,000 ppm, or5,000 ppm, and preferably 10,000 ppm and more preferably 15000 ppm. Suchconcentrations of ammonia are strongly antimicrobial and directlysensitize very retractile microorganisms such as microbial spores,cysts, and parasite eggs to additional stresses such as acid pH exposureand or heat exposure. High concentrations of ammonia will affect themembranes of microorganisms. The present invention does not need theammonia to kill the microbial pathogens present, but only needs tosensitize them making exposure to subsequent acidification, and or heat,more effective in destroying these organisms. The concentration ofammonia added to the mix can be raise the concentration of nitrogen inthe mix by 6%, preferably by 10% and more preferably by 14%. A portionof this ammonia can be added after the acidification step to avoidcreating too much gaseous nitrogen. Adding a portion of the ammoniaafter acidification will facilitate the production of ammonia salts suchas ammonium sulfate or ammonium phosphate. Some additional acid may needto be added after this second ammonia addition in order to react withany free ammonia and to adjust the pH to between pH 5.0 and 7.0.

The present invention improves and broaden the art of municipal sludgetreatment and fertilizer manufacture by making a safe valuableinorganically augmented organic combined fertilizer.

The graph in FIG. 1 and the diagram in FIG. 2 illustrate the steps andassociated pH changes that occur during the treatment of a biologicalsludge or biosolids with the present invention. Step 1 represents thestarting pH of the untreated dewatered biological sludge or biosolids.Further, the starting ammonia concentration in the untreated sludge wasabout 15 ppm. Step 2 is the conditioning step in which the biosolids orsludge is rendered thixotrophic or into a paste-like consistency. The pHand the ammonia concentration did not change. In step 3, an alkalinematerial selected from calcium oxide, calcium hydroxide, potassiumhydroxide, sodium hydroxide, alkaline by products such as cement kilndust, lime kiln dust, Class C fly ash, Class F fly ash, lime injectedfly ash or other high alkaline materials, is added and mixed directly tothe biological sludge. This causes the pH to rise, as in this example topH 11.0. This pH rise causes ammonium ion present in the biologicalsludge to convert to gaseous ammonia and begin the disinfection process.

As a consequence, the free ammonia concentration rose to 2000 ppm. Instep 4 additional 9% waste aqueous ammonia is added. This ammonia mayalso be anhydrous or may be other aqueous percents such as the commonlyused 29% aqueous ammonia used in commercial fertilizer protocols. As aconsequence; the free ammonia rose to over 10,000 ppm. At theconcentrations in step 4 and step 5, ammonia is diffusing into themicroorganisms present, causing damage to the cells and cell membranes,and decreasing their subsequent resistance to additional stresses suchas acidification and or the application of heat during additional mixingsteps or during granulation and drying. The ammonia exposure in the mixshould be for a period of about 30 seconds, preferably for about 2minutes and more preferably for over 5 minutes. During the period ofammonia exposure that the mix be agitated to maximize exposure ofmicroorganisms contained in the sludge to the ammonia. In step 5, anacidification takes place, in this example using waste black phosphoricacid at 65% P₂O₅. This step reduces the pH to the physiological friendlypH ranging from pH 5.7 to pH 7.0, preferably to pH 6.5. The reaction ofthis acid with the ammonia present in the mix creates ammonium phosphateand will release exothermic heat into the mix. This heat, greater than176 degrees Fahrenheit (80° C.); preferably greater than 212 degreesFahrenheit (100° C.) and more preferably greater than 250 degreesFahrenheit (121° C.), following the ammonification earlier, willcontinue the disinfection process. This acidification step will reducethe ammonia concentration significantly—in this example, to 10 ppm.Further; the ammonium phosphate now formed in the reacted mix willcontribute plant nutrient value to the final product. In the final Stepin this example, other nutrients are added, selected from the groupcomprised of ammonium sulfate, ammonium nitrate, mono-ammoniumphosphate, di-ammonium phosphate, potash, urea, ferric oxide, and ferricsulfate and the mix is processed using conventional granulation anddrying technologies into the finished hard, dry granular fertilizerproduct. Further, liquid fertilizers, such as urea ammonium nitrate(“UAN”), and or aqueous urea, can be blended into the mix followingacidification. The concentration of free ammonia will continue todrop—in this example, to approximately 3 ppm.

FIG. 2 of the Alkaline Ammonification Pulse (“AAP”) process shows thesteps used to create a valuable fertilizer product starting with anorganic sludge. The pH and the ammonia concentration are represented assteps. Step 1 represents the biosolids as they enter the process. Step 2is immediately after the biosolids are rendered thixotrophic. Step 3 isupon addition of the alkaline material to the process initiallyincreasing the ammonia concentration. Step 4 adds additional ammoniarequired to raise the ammonia concentration in the mix to over 10,000ppm. Step 5 is following acidification of the mix. Step 6 is theresultant pH and ammonia concentration at completion of the process ofthe invention.

Overall, the dewatered municipal biosolids at a concentration ofapproximately 25 percent solids. In the AAP process, the preferredpractice is to place the processing plant at or near the biosolidsgenerating plant, preferably the wastewater treatment plant (“WWTP”).One purpose of the close proximity of the AAP processing plant with theWWTP is to reduce logistics and liability associated with moving thesludge or biosolids from the WWTP to the AAP plant as well as to retainthe processing capability of returning extracted water from thebiosolids back to the WWTP thereby preventing the necessity ofdischarging this water into the aqueous or atmospheric environment. Bynot having to transport the amount of water contained in dewateredbiosolids to a distant biosolids processing plant a large economicsavings can be an advantage.

The initial step in the AAP process as shown in FIG. 1 is to convert thedewatered biosolids cake into a thixotrophic material, preferably apaste-like consistency without the addition of water or other materialsto the biosolids or sludge. This is accomplished efficiently using thepreferred method of introducing the biosolids into a plow blenderdual-shafted pugmill or other vigorous mixer, which will agitate and mixthe biosolids into the thixotrophic consistency. Following this step,the biosolids can be deodorized if necessary, by the introduction intothe pugmill or mixer or an additional pugmill or mixer of an oxidant, inthis example, a chlorine dioxide, which oxidatively modifies the reducedsulfur, amine and organic odors to an acceptable level. Alternatively,the addition of calcium ferrate or potassium ferrate can be added as theoxidative step. The addition of ferrate has the advantage here sinceferrate is a powerful oxidant that has the ability not only to oxidizereduced sulfur compounds and other odorants, it can denature protein andother organic molecules present in the sludge thereby reducing oreliminating their odor or biological activity. Further, the addition offerrate, following the oxidation, causes valuable iron to be part of thenutrient chemistry of the final product. The next step in the procedure,for which this method obtains its title, is the addition of an alkalineagent, in this example; the addition of an amount of lime kiln dustcontaining calcium oxide, which raises the pH of the mix to greater thanpH 10.0 and in this example to pH 11.0. This increase in pH will causethe liberation of a significant proportion of the ammonium ion presentinto free ammonia. This free ammonia will commence the disinfectionprocess for the biosolids. To insure that disinfection is significantand that sufficient nitrogen is added to the mix to form a valuablefertilizer, the next step is an ammonification of the mix by theintroduction of an ammonia containing material, in this example, using9% aqueous ammonia, to raise the ammonia concentration in the mix togreater than 10,000 ppm and in this example to 15,000 ppm. Thisconcentration of ammonia will cause membrane damage to themicroorganisms present and continue the disinfection process. Manymicroorganisms will die as a result of this treatment; however, it isnot necessary for all of the pathogens present to be killed by thisstep. What does happen is that this ammonification is a significantstress to the pathogens present and renders them more sensitive tosubsequent antimicrobial stresses of acidification and ultimately in theprocess of this invention to heat exposure, greater than 176 degreesFahrenheit (80 degrees Celsius), preferably above 212 degrees Fahrenheit(100 degrees Celsius) and more preferably above 250 degrees Fahrenheit(121 degrees Celsius), such that the resultant product is safe from apublic health perspective. The product of this invention meets the U.S.EPA's Class A standard for products containing a percentage of municipalbiosolids.

The ammonification step occurring in a pugmill or mixer is then followedin a subsequent pugmill, by the acidification of the mix. Preferably,and in this example, phosphoric acid is added, in this case 65% wasteblack phosphoric acid, such that the pH in the mix is reduced to belowpH 7.0 and in this example to pH 6.5. Various plant nutrients are thenadded, such as diammonium phosphate (“DAP”), ammonium sulfate, urea,potash (“KCI”), and or ferric oxide to create a plant nutrientconcentration that is suitable for marketing the product as a commercialfertilizer. In this example, the nutrients added caused the mix, in thefinal product, to equal, on a weight percent basis a 10-10-10-0-1-20(N—P—K—S—Fe-Organic) fertilizer. Further, granulating agents, such asindustrial molasses or proprietary binding agents, are added here tofacilitate the granulating process to convert the mix into sphericalgranules. The mix is then moved to a granulator dryer to create aproduct with a preferred diameter of between 2.0 mm and 3.5 mm,preferably and in this example to 2.7 mm. The proper diameter is insuredby moving the granules through a screen system with the reject sizesbeing milled and recycled to the granulation system. The proper sizedgranules are cooled, and optionally coated with a material to preventthe dusting of the granules during storage and shipment. Further, theoptional coating material is selected, in the Present invention, toretard the emission of any odorants remaining in the granules. Finallythe granules are moved to dry storage until shipment. Preferably, thegranules have a dryness of 90% or more solids.

The present invention accomplishes at least the following:

A. The creation of a high value fertilizer granule employing an alkalineand ammonia stabilization strategy.

B. That sludges or biosolids to be treated may be comprised of municipalbiosolids or sludges, manures or animal residuals, or from organicsludges as produced from food fermentation wastes or pharmaceuticalfermentation wastes.

C. The production of a commercially viable amount of plant nutrientcontent in finished fertilizer granules.

D. Methods to reduce the odors associated with organic containingsludges during the production of inorganic augmented-bioorganicfertilizer granules.

E. The first step in treating organic containing sludges is to convertthem to a thixotrophic or paste-like mix.

F. Following conversion to a thixotrophic paste the addition of analkaline agent to the mix will cause the ammonium ion present to convertto free ammonia.

G. An additional pulse of ammonia can be added to bring the free ammoniaconcentration to over 1000 PPM and preferably over 10,000 PPM and morepreferably over 20,000 PPM.

H. Nutrient enhancement may come from directly adding dry or liquidfertilizers to the mix before it is granulated and dried.

I. The reduction of odors and addition of plant nutrients to saidfertilizer granules.

J. Reduction of odors and addition of plant nutrients to occursimultaneously in the production of said fertilizer granules.

K. The introduction of a multiple sequential antimicrobial stressesduring the manufacture of fertilizer granules.

L. Concentrated acid is added to ammoniated dewatered biosolids asignificant exothermic heat reaction will occur which will introduce aphysical heat disinfecting process to the biosolids prior to thegranulating and drying steps in the manufacture of fertilizer granules.M. The production or manufacture of a valuable fertilizer capable ofbeing sold into the commercial agricultural marketplace.N. Treats biosolids or organic containing sludges to increase the levelof plant nutrients, that will be contained and plant available in thefinished dried pellet or granule. The chemical additions are made todewatered biosolids. The chemical additions are added to the dewateredbiosolids by means of a mixer, such as a pugmill, preferably adual-shafted plow-bladed pugmill, that blends the additives with thebiosolids mix such that the additives have the opportunity to completelyinteract and react with the chemical components of the biosolids.

In one embodiment of the invention, an alkaline material is added to theorganic sludge after the sludge is converted into a thixotrophicpaste-like material and after the sludge has been oxidized with anoxidizing agent such as calcium ferrate. This alkaline step is followedby an addition of more ammonia via either aqueous ammonia or anhydrousammonia. Concentrated acid or mixture of concentrated acids, such asphosphoric acid and/or sulfuric acid is/are introduced to the ammoniatedmix. Further; the acid pH created by such acid addition is within therange of pH 4.0 to 7.5, preferably from pH 5.0 to 7.0 and preferably toa narrower range of pH 5.8 to pH 6.8. Such a desirable pH range ispreferred by fertilizer distributors and/or the grower/farmer finalcustomer of the product of this invention. The effect of thisinteraction and reaction is to lessen the odor associated with thefinished heat dried product and to increase the plant nutrient chemicalcontent and value of the finished heat dried product. Concentratedphosphoric acid, as 70% super phosphoric acid and/or 50-65% phosphoricacid (black or green, agricultural grade phosphoric acid) is addeddirectly to the ammoniated mixture. The addition of phosphoric acid notonly reduces the odor associated with such biosolids, but simultaneouslyincreases the phosphorus (P) content of the finished product. Thegeneration of ammonia by addition of alkaline admixture to the biosolidsas well as by direct additions of ammonia, either as aqueous ammonia oranhydrous ammonia or ammonium ions, will have a disinfecting role indestroying pathogens that are contained in the dewatered biosolids priorto the drying step of fertilizer granule manufacturing process.

Further, the present invention involves oxidants such as such as calciumferrate or potassium ferrate or sodium ferrate, hydrogen peroxide,oxygen, ozone, sodium hypochlorite and calcium hypochlorite and chlorinedioxide in reducing odor of organic containing sludges prior to theirbeing treated with the alkaline agent and the ammoniating agent.Further, the invention teaches the use of iron oxide and other forms ofiron, such as iron sulfate which can be mixed in directly with thealkaline mix.

Further, the process employs one or more nutrient fertilizer materials,such as ammonium sulfate, ammonium nitrate, mono-ammonium phosphate,di-ammonium phosphate, and urea and further, may be selected from thegroup of liquid fertilizers, such as urea ammonium nitrate (“UAN”),liquid urea or from other liquid N—P—K fertilizers such as, for example,16-4-8, 10-8-8, or 6-14-6.

Other embodiments and uses of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. All references cited herein,including all publications, U.S. and foreign patents and patentapplications, are specifically and entirely incorporated by reference.It is intended that the specification and examples be consideredexemplary only.

1. A method of fertilizer manufacture comprising: creating a thixotropicpaste from a composition containing biosolids; adding an oxidizing agentto the paste; adding a first amount of ammonia to the paste to produce apH of 10 or higher; adding an acid to the paste to produce heat and atpH 7.0 or less and a second amount of ammonia to the paste to raise theconcentration of free ammonia to above 10,000 ppm; adding a granulatingagent to the paste; extruding or granulating the paste; and drying theextruded or granulated paste to a dryness of 90% or more of solids. 2.The method of claim 1, wherein biosolids are selected from the groupconsisting of municipal biosolids and sludges, manures and animalresiduals, lagoon sludges, organic-containing sludges produced from foodfermentation, sludge waste products, pharmaceutical fermentation waste,industrial fermentation products, and mixtures and combinations thereof.3. The method of claim 1, wherein the oxidizing agent is selected fromthe group consisting of hypochlorite, sodium hypochlorite, calciumhypochlorite, iron oxide, metal oxide, calcium ferrate, potassiumferrate, sodium ferrate, oxygen, hydrogen peroxide, peroxide, ozone,chlorine dioxide, and combinations thereof.
 4. The method of claim 1,further comprising adding additional acid after the step of adding asecond amount of ammonia.
 5. The method of claim 1, wherein, afteraddition of the first amount of ammonia, the mixture is pH 11 or higher.6. The method of claim 1, wherein the ammonia is aqueous or anhydrousammonia.
 7. The method of claim 1, wherein the dried paste has a pH ofbetween 5.0 and 7.0.
 8. The method of claim 1, wherein the concentrationof ammonia is at least 20,000 ppm.
 9. The method o claim 1, wherein theconcentration of ammonia provides a dry weight nitrogen concentration of6%.
 10. The method of claim 1, wherein the concentration of ammoniaprovides a dry weight nitrogen concentration of 10%.
 11. The method ofclaim 1, wherein the concentration of ammonia provides a dry weightnitrogen concentration of 14%.
 12. The method of claim 1, wherein theacid is selected from the group consisting of phosphoric acid, sulfuricacid, sulfamic acid, hydrochloric acid, nitric acid and combinationsthereof.
 13. The method of claim 1, wherein, after treating with theacid, the paste is pH 7.0 or less.
 14. The method of claim 1, furthercomprising blending a plant nutrient with the thixotropic paste toincrease one or more of nitrogen, phosphorus or iron content of thepaste.
 15. The method of claim 14, wherein the plant nutrient content ofthe dried paste is at least 8% nitrogen by dry weight.
 16. The method ofclaim 14, wherein the plant nutrient content of the dried paste is atleast 12% by dry weight.
 17. The method of claim 14, wherein the plantnutrient content of the dried paste is at least 15% by dry weight. 18.The method of claim 1, wherein odor associated with the dried paste isreduced.
 19. The method of claim 1, wherein the thixotropic paste istreated with an oxidizing agent such that odorant emission from thedried paste is reduced simultaneously with increasing plant nutrientconcentration.
 20. The method of claim 1, wherein the extruded pasteformed into pellets or granules.
 21. The method of claim 20, wherein thepellets or granules are coated.
 22. The method of claim 1, furthercomprising storing the dried paste in a dry environment.
 23. The methodof claim 1, further comprising applying the dried paste to plants as afertilizer.
 24. The method of claim 1, further comprising applying anantimicrobial stress during any step.
 25. The method of claim 24,wherein the microbial stress is selected from the group consisting of apH greater than pH 10, a pH greater than pH 11.0; free ammoniaconcentration in the paste at greater than 1,000 ppm, free ammoniaconcentration in the paste at greater than 10,000 ppm; free ammoniaconcentration in the paste at greater than 15,000 ppm; heat at greaterthan 80° C.; greater than 100° C., heat at greater than 121° C. andcombinations thereof.
 26. The method of claim 1, further comprisingadding a fertilizer to the dried pellets or granules to provide nutrientenhancement.
 27. The method of claim 26, wherein the fertilizer isselected lion the group consisting of dry fertilizers, liquidfertilizers, ammonium sulfate, ammonium nitrate, mono-ammoniumphosphate, di-ammonium phosphate, urea, urea ammonium nitrate (“UAN”),liquid urea, N-P-K fertilizers, 16-4-8, 10-8-8, 6-14-6, and combinationsthereof.
 28. A method of converting biosolids into fertilizer,comprising: mixing the biosolids to a homogenous paste; adding a firstamount of ammonia to the homogenous paste to raise the pH of thehomogenous paste to above 10.0; adding an acid to the basic homogenouspaste to lower the pH of the basic homogenous paste to below 7.0; addingsecond amount of ammonia to the acidic homogenous paste to raise theconcentration of free ammonia to above 10,000 ppm; and adding nutrientsto the paste to create the fertilizer.
 29. The method of claim 28,further comprising adding additional acid after the step of adding asecond amount of ammonia.
 30. The method of claim 29, wherein thefertilizer has a final pH of between 5.0 and 7.0.
 31. The method ofclaim 28, further comprising: adding a granulating agent to the paste;granulating the paste; and drying the granulated paste to a dryness ofat least 90% of solids.
 32. The method of claim 31, wherein thegranulated paste is formed into pellets or granules.
 33. The method ofclaim 32, wherein the pellets or granules are coated.
 34. The method ofclaim 28, wherein the biosolids are selected from the group consistingof municipal biosolids and sludges, manures and animal residuals, lagoonsludges, organic-containing sludges produced from food fermentation,sludge waste products, pharmaceutical fermentation waste, industrialfermentation products, and mixtures and combinations thereof.
 35. Themethod of claim 28, wherein the ammonia is aqueous or anhydrous ammonia.